Abstract: A GPSR multi-frequency measuring ionospheric delay correction mechanism comprises an ionospheric delay corrective section for estimating an ionospheric delay coefficient based on pseudo-range data measured as an observation on multi-frequency, and for generating an ionospheric delay corrected pseudo-range based on the estimated ionospheric delay coefficient. The pseudo-range data measured as the observation on multi-frequency by using the GPS receiver or the positioning tool is acquired, and the ionospheric delay coefficient is estimated based on the pseudo-range data. An ionospheric delay corrected pseudo-range is then generated using the estimated ionospheric delay coefficient.